1 / 17

Lecture 6

Lecture 6. CSE 331 Sep 9 , 2013. Homeworks. HW 1 posted online: see piazza. Pickup graded HW 0 in TA OHs/recitations. Comments on feedback. 70% on exams and 4% on group project seems uneven (unfair? ) . Distribution proportional to time spent preparing for it. Aside: Do your HWs!.

mort
Download Presentation

Lecture 6

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 6 CSE 331 Sep 9, 2013

  2. Homeworks HW 1 posted online: see piazza Pickup graded HW 0 in TA OHs/recitations

  3. Comments on feedback 70% on exams and 4% on group project seems uneven (unfair?) Distribution proportional to time spent preparing for it.

  4. Aside: Do your HWs! Fall 2011 Fall 2012

  5. Another comment Discomfort with proofs I will not cover proof basics in class Please come and talk to us in person if you need help

  6. Lecture pace Mid-term

  7. Online Office Hours Tomorrow: 9:30pm to 10:30pm

  8. Questions/Comments?

  9. Gale-Shapley Algorithm Intially all men and women are free While there exists a free woman who can propose Let w be such a woman and m be the best man she has not proposed to w proposes to m If m is free (m,w) get engaged Else (m,w’) are engaged If m prefers w’ to w w remains free Else (m,w) get engaged and w’ is free Output the set S of engaged pairs as the final output

  10. Today’s agenda Run of GS algorithm on an instance Prove correctness of the GS algorithm

  11. Preferences Mal Inara Wash Zoe Simon Kaylee

  12. GS algorithm: Firefly Edition Inara Mal Zoe Wash 4 5 6 1 2 3 Kaylee Simon 4 5 6 1 2 3

  13. Observation 1 Intially all men and women are free While there exists a free woman who can propose Let w be such a woman and m be the best man she has not proposed to w proposes to m If m is free (m,w) get engaged Once a man gets engaged, he remains engaged (to “better” women) Else (m,w’) are engaged If m prefers w’ to w w remains free Else (m,w) get engaged and w’ is free Output the engaged pairs as the final output

  14. Observation 2 Intially all men and women are free While there exists a free woman who can propose Let w be such a woman and m be the best man she has not proposed to w proposes to m If m is free If w proposes to m after m’, then she prefers m’ to m (m,w) get engaged Else (m,w’) are engaged If m prefers w’ to w w remains free Else (m,w) get engaged and w’ is free Output the engaged pairs as the final output

  15. Questions/Comments?

  16. Why bother proving correctness? Consider a variant where any free man or free woman can propose Is this variant any different? Can you prove it?

  17. GS’ does not output a stable marriage

More Related